Double glazed window



May 23, 1939.

P E. KN'UDSEN DOUBLE GLAZED WINDOW Filed March 1, 1938 A mama's.

J condense upon the inner surfaces thereof.

Patented May 23, 1939 UNITED STATES PATENT OFFICE DOUBLE GLAZED WINDOW Percy E. Knudsen, Pittsburgh, Pa., assignor to Pittsburgh Plate Glass Company, Allegheny County, Pa., in, corporation of Pennsylvania Application March 1, 1938, Serial No. 193,297

9 Claims.

The present invention relates to window constructions notably of the double glazed type in which two on more panes of glassare disposed .in a suitablepframe in spaced parallel relation l with respect to each other in order to provide" a dead air space of low heat conductivity.

One object of the invention is to obviate condensation of moisture and resultant staining! action upon the inner surfaces of the sheets of 10 glass comprising double glazed windows.

I A second object of the invention is to provide apparatus for eifecting the foregoing purpose which is automatic in its operation and requires little or no attention upon the part of the users 16 of the constructions.

a common form of double glazed window construction comprises a pair of spaced parallel sheets or panes of glass suitably secured together in a frame thereby providing a dead air space or chamber which eifectively insulates the units against the transmission of heat of convection or conduction. Insuch units considerable difliculty is occasioned by a tendency of watervapor to get between the sheets of glass and to condensedvapor of course tends to obscure vision through units; furthermore, the water seemsto attack or decompose the surface film of glass thus occasioning permanent stains. In order 30 to obviate this condensation of water vapor it has been. proposed toprovide openings preferably through the frame of the units into the dead air space thus permitting sufficient circulation of the air to remove by evaporation any water which 35 has accumulatedupon the surface of the glass.

Such constructions obviates the formation of permanent films of water vapor, but it sometimes happens that the atmosphere upon one side of the units will be relatively warm and saturated with water vapor while the atmosphere upon 0 where the temperature is relatively constant and the atmosphere within the buildings during the summer months may besubstantially colder and drier than the atmosphere outside-oi the building, while in the winter time conditionsare reversed.

,- 5 In the usual constructions it is impossible to in-.-

Such- This effect is sure that the air will always be circulated into the units from the cold side in such manner that it will be warmed upon entrance into the air chamber, and therefore will not tend to deposit moisture.

In a unit constructed in accordancewith the' provisions of the present, invention openings are provided in. the double glazed units extending from opposite sides thereof into the dead air chamber and a-thermostatically-controlled valve is provided which is so constructed as automatically to prevent the entrance of air fromthe warmer side of the glass when the temperature of the atmosphere about the building fluctuates.

In the drawing in which like numerals refer to like parts throughout a double glazed unit constructed in accordance with the provisions of the present invention comprises a pair of spaced sheets of glass 4 and 5, the former of which may be somewhat thinner than the latter and pref- 2o erably constitute the interior pane in the unit. .The panes are disposed in grooves 6 in a frame I, which, as shown in the drawing, is solid or unitary. However, if desired, the frame may comprise outer and inner sections suitably hinged together along one edge in such manner that should occasion arise the unit may. be opened up to permit cleaning of the inner surfaces thereof. The frames. may be designed for vertically sliding in suitable easements or if preferred they may be of the conventional casement type and hinged atone edge to permit them to swing open. As shown'in the drawing the frame I rests at its lower edge upon a sill or ledge 8 of conventional design and constitutes a part of a building which terial such as activated alumina are secured in the space back of the plugs l3 and I4 and act partial- 1y or completely to dehydrate air which circulates 2 of a valve 22 is'disposed therein. This valve on opposite sides is of conical contour and is designed selectively to mate with corresponding countersunk seating portions 23 and 24 at the .metallic element are so selected that as the external atmosphere about the outer pane fluctuates with respect to the atmosphere about the inner pane 4 the position of the valve 23 will be changed to insure that only the colder air is admitted to the interior of the unit.

The mode of operation of the construction herein disclosed is practically self evident from the foregoing description. It will be assumed for purposes of illustration that the atmosphere out-' side of the building in which the units are employed is substantially colder than the atmospherewithin the building. Under such conditions the metallic element 26 will tend to straigten out, thus causing the valve 22' to move inwardly, to prevent the admission of relatively warm air from the interior of the building. The cold dry air from the exterior of course when it enters the space between the sheets 4 and 5 will tend to become warm and therefore its capacity to retain water vapor will be increased, and there can be no deposition of surface film of moisture upon the glass.

Similarly, if the interior of the building is colder than the exterior, as often occurs in air-conditioned buildings, the by-metallic ele- 'ment 26 which is in contact with glass 5 will become warm and will cause the valve 22 toswing outwardly to close the unit tothe relatively warm external atmosphere. In event that the atmosphere upon opposite sides of the units are at substantially the same temperatures the valve 22 will-assume a neutral position in which the entrance of air from both sides permitted.

The principal advantage of the above described construction resides in the fact that the operation of the valve for controlling the adof the units is l mission of air to the units is entirely automatic,

, assuring that at all times the interior surfaces of thus precluding the possibility of neglect upon the part of the occupants of the building and the sheets of glass in the unit will be free of moisture and that there will be no tendency to cause blooming or eflloresence of the glass.

Although only a preferred form of the invention has been shown and described, it will be apparent to those skilled in the art that numerous modifications may be made therein without departure from the spirit of the invention" or the scope of the appended claims.

What I claim is:

l. A multi-glazed window construction comprising a plurality of sheets of glass secured in spaced parallel relation in a frame to provide a dead air chamber, said frame having inlets formed therein and providingcommunication between opposite sides of the window and the dead air space between the sheets of glass, valve mechanism disposed selectively to prevent entrance of air from one side of the unit, and temperature-controlled means for operating the valve to prevent air from entering the unit from the warmer side thereof.

2. A construction as defined in claim 1 in which the temperature-controlled means is governed by the temperature of the external sheet of glass.

3. A construction as definedin claim 1 in which the temperature controlled means comprises a bimetallic element having one extremity secured to the valve and having the other extremity maintained in contact with the external sheet of glass.

4. A construction as defined in claim 1 in which porous filter plugs are disposed in the passageways. J!

5. A construction as defined inclaim 1 in which dehydrating units are disposed in the passageways.

' 6. A building construction comprising a win dow having spaced inner and outer sheets of glass, air ducts connecting the space between the sheets respectively with the atmosphere within the building and the external atmosphere, a

valve in the ducts and a thermostat for actuat-- ing the valve selectively to close one of the ducts, depending upon the external temperature about the building.

'I. A construction as defined in claim 6 in which the thermostat comprises a thermally sensitive actuating element in contact with the outer sheet of glass.

8. A construction as defined in claim 6 in which the building is air conditioned.

' 9. A construction as defined in claim 1 inwhich the thermally responsive element is in contact with the lower portion of the outer sheet of glass.

PERCY E. KNUDSEN. 

